Expanding mandrel



Oct. 18, 1932.

' e ANDERSON EXPANDING MANDREL Filed April 50, 1930 Patented Oct.18,1932

' uni-TED;STATES PATENTJ oFFlcs GUSTAVE ANDERSON, or BERLIN, NEWnnmrsnmnnssrcnon T0 BROWN COMPANY; or BEBVLIN, NEW HAMPSHIRE, ACORPORATION or. MAINE EXPANDILTG MANDREL.

Application filed April 30, 1930.1 ,Serial' No; 448,588;

This invention relates to an expanding mandrel adapted to be inserted inthe interior of hollow bodies, such as tubes or the like, and to beexpanded so as to grip the article firmly.

An object of the invention is to provide a structure which is not onlyeflicient in operation, but which is light, strong and inex-j pensive.

For a more complete understanding of the invention, reference may be hadto thedisclosure thereof in the following description and on thedrawing,gof Which,

Figure 1 is an end elevation of a'mandrel embodying the invention.

Figure 2 is a side elevation, a portion being mandrel may include a pairof end plates 10,

which, as shown, are annular in-shape if intended for holding a. tubularobject. The

outer diameter of the plates is suificiently less than the innerdiameter of the object to be held to permit the ready insertion of themandrel into the object.- These plates may be held in parallel relationby a number "of longitudinal tie-rods 11 which may be secured at theirends to the respective plates by any de-' sired means such as riveting,spot welding, or a screw threaded connection. A number of expandingpieces 12 are assembled with the end plates before the latter aresecured to the tie-rods 11. The expanding pieces may be of generallyrectangular shape, as shown in Figure 4, and are provided with a notch13 at each end having a depth which may be substantially equal to thethickness of an end plate 10. On either side of the notch 13 are lugs14, 15. The end plates are provided with a series of inner radialslots16 and outer radial slots 17, the inner and outer slots beingarranged in pairs on common radii. Between each pair of slots is left aneck or bridge 18 which enters the notch 13 when the parts are assembledso thatthe lugs 14,- 15

enter-respectively the slots 16 and-17. .The

overall length ofeach expanding piece 12 may be equal to the distancebetween the outer faces of the two end plates 10, so as to make the endsof the lugs 14, 15 substantially flush wlth the outer faces of the end.plates,'but the lugs14, 15 may project beyond the end plates ifdesired. The width of the expanding pieces 12 is somewhat greater thanthe widthofthe annulus 10, so that the inner edges of the expandingpieces 12 project within the lnner circles of the end plates 10, as isshown in Figure 1, when the outer edges of the expanding pieces areflush with the outer circles of theend plates. The slots17 areperferablycut substantially equal to the cross section of the lugs 15 so that theouter edges of the'pieces are flush with the outer circles of the endplateslO. Theslots 16 are also preferably shaped to fit the lugs 14 sothat the inner edges of the expanding pieces 12 are flush with the innercircles of the end plates 10 when the lugs 14 are against the necks 18.The outer edges of the expanding pieces maybe provided with one or morenotches 20, two suchnotches being illustrated in Fig ure 4. Thesenotches are made sufliciently deep to receive a circular spring 21Whichmay be sna-ppedinto place and is adapted to hold theexpandingpieces ,12 yieldingly in their inward position, asillustratedin Figures 1 and 3. The lower cornersof the expanding pieces'12 are. preferably rounded as at 22 so as to ride easily on conicalwedging pieces which enter the ends of'the mandrel for; the purpose ofexpanding it., A suitable arbor for use with'this type of mandrel isillustrated in Figure 5. .This arbor may comprise a pair of members 23and 24 which .are provided with opposed frustoe conical "cam surfaces onwhich the lower cor ners 22 of the expandingpieces 12 may rest. Astandard 25 may be provided to support the mechanism, this standardhaving a quill 26 secured thereto,'as by a set-screw 27, .so' thatthequill is therebyheld against rota: tion. The member 24 may be keyed;to the tually adjacent ends of thejmembers and.

' quill 2 6 as by a suitable spline 29, The mu- 3 24 may be crenelatedwith inter-engaging fingers as at 28, the projections of one memberfitting slidably into the recesses ofthe other member so that the twomembers are held against relative rotation, but are free to move axiallytoward and away from each other. The members 23 and 24 are hollow andare internally threaded with right and left hand threads respectivelyfor engagement with the threaded end of a spindle 30, this spindle beingrotatable by any suitable means such as a knurled finger wheel 81. Sincethe members 23 and 24 are both held against rotation, it is obvious thatrotation of the spindle 30 will move the members v toward oraway fromeach other according to the direction of rotation of the spindle, theaxial movement of the members being brought about by the right and lefthand threads when the spindle 30 isrotated'so as to cause the members23, 24 to move toward. The wedging action of their frustoconical facesresults in the expand ngw each other.

pieces 12 being forced outwardly to grip the interior of a tube or otherarticle which has the springs21 draw the expanding pieces 12.

inwardly to a position flush witht'he "outer signature.

edges normally flush with the outer edges of the end plates and inneredges normally Within the inner edges of the end plates, each saidexpanding piece having a pair of lugs on each end entering a pair ofnotches in said end plates, the distance between the lugs of each pairbeing greater than the distance between the notches of each pair, andmeans for resiliently holding said expanding pieces in their inneriosition.

In "testimony whereof I have afiixed my GUSTAVE nnnnson.

edges of the endplates so that the arm-1e I which has been'held'iby themandrel can be removed therefrom. This mandrel is light,

strong, and inexpensive, and not only holds I the worlrfirmly butalsoicente rs'it accurately. The mandrel illustrated on-thedrztwingisshaped for holding hollow f cylindrical objects such as tubes, butit isobvious that the external contourof the end plates may vary for use inholding objects having hollows of other shapes. 7

I claim: p I

1. An expandingmandrel comprising a pair ofannul'ar endpl'ates, eachsaid endplate having a series of radial slots extending outwardly fromthe inner edge'thereof, there being 'a corresponding series of radialslots extending inwardly from the outer edge thereof, means for holdingsaid end plates rigidly in a 'parallel'coaxial relation withcorresponding slots in alignment, a plurality of expanding pieces havingouter edges normally flush with the 'outer edges of the end plates andhaving a pair'of lugs on. each end the'reof'projecting into a pair ofslots in said end plates, and means for resiliently holding theexpanding pieces in their inner position. 2. An -expanding mandrelcomprising a pair of annular plates having a series ofradial notchesextending outwardly from the inner edge thereof, there being acorresponding series of radial notches extending inwardly from the outeredge thereof, meansfor holdplurality of expanding pieces having outer

